Central venous catheters (CVCs), such as peripherally inserted central catheter (PICC) lines, are long term implants (i.e., several weeks to months) used for central venous access. PICCs are widely used in many applications including: administration of pain medication, antibiotic drug delivery, blood sampling, blood transfusions, chemotherapy, hydration, total parenteral nutrition, hemodialysis, and other long term fluid administration applications. The accurate placement of PICC lines is not trivial and generally requires patient informed consent and placement by a specialized team member, whose sole focus is on PICC line delivery. Placement of the lines can occur in various locations including the operating room, during radiological procedures, at bedside in the clinic, or at home.
Proper placement of the CVC is crucial for the long term safety of the patient as well as efficacy of the catheter. Improper placement can result in arrhythmias, cardiac tamponade (i.e. catheter perforation), catheter dysfunction (e.g. obstruction or breakage), catheter-related sepsis, mechanical phlebitis, or thrombosis. These complications result in added clinical time and cost and, if left unattended, can ultimately lead to patient death. The ideal location for the PICC line tip in the vasculature that will minimize the risk of these complications has been a topic of debate. Several locations such as the right atrium (RA), the cavoatrial junction, and the superior vena cava (SVC) have been recommended; however, the general consensus is that tip placement should occur in the lower one third of the SVC for safe and effective usage.
CVCs, including PICC lines, are traditionally inserted using general medical personnel feel, one or more x-rays of the patient, and potentially also using ultrasound and/or fluoroscopy. Such procedures are not only time intensive, but also cost intensive in connection with the various scans and x-rays, and the longer the duration of the procedure, the more discomfort to the patient. In addition, and should the CVC not be properly placed, any therapy delivered therethrough may not be properly delivered, and the CVC itself could cause complications if improperly advanced into the heart.
Although x-ray confirmation is highly recommended for CVC placement, there are certain limitations that can make it unfeasible and/or unreliable. In many situations, such as home-care, seriously-ill, or emergency care situations, fluoroscopic guidance may not even be possible. When fluoroscopy or x-ray is possible, there are certain patients (like the morbidly obese or patients with spinal implants) in which visualization of the heart and vasculature can be difficult and make CVC placement challenging. In addition, x-ray guidance is inaccurate because it relies on interpretation of a two-dimensional projection of a three-dimensional object (the heart and vasculature and the soft nature of the tissue). Among Radiologists, discrepancies in the interpreted location of catheter tip position for AP chest x-ray images has been shown to occur in 40% of the cases. Thus, several studies have attempted to help clinicians locate the correct spot for the CVC tip by correlating x-ray landmarks (e.g., the carina to cavoatrial distance) with more precise computed tomography (CT) or magnetic resonance imaging (MRI) images. However, these approaches demonstrated patient variability in the landmarks (i.e., almost a 3 cm patient to patient range in landmarks), and hence, have not been widely utilized in clinical practice.
Based on the inherent limitations of fluoroscopy and the FDA's desire to develop new methods to reduce the amount of radiation exposure for both the patient and the clinician, efforts have been made to develop new PICC line guidance technologies. These new methods have included the use of monitoring changes in electrocardiographic waveforms and/or Doppler flow patterns as well as echocardiography and stylet-aided magnetic guidance. All of these existing technologies have inherent limitations because they attempt to find anatomical positions based on physiological measurements (ECG, flow measurements, etc.). There is a need for an anatomically-based, non-fluoroscopic method for accurate PICC line delivery that will require little training, be cost effective, portable, and reliable across various patient populations.
Devices and methods of positioning PICC lines and other CVCs accurately and with less time and cost would be well received by medical personnel, such as, for example, a novel conductance guidewire (CGW) system that provides real-time, simple feedback to the clinician for accurate PICC line placement without the assistance of x-ray guidance.